Study of GA-GCB Enzyme Replacement Therapy in Type 1 Gaucher Disease Patients Previously Treated With Imiglucerase

Inclusion Criteria: Includes: * The participant has a documented diagnosis of type 1 Gaucher disease, as determined by deficient glucocerebrosidase (GCB) activity relative to normal as measured in leukocytes or by genotype analysis and the participant/legal guardian is willing and able to provide written informed consent prior to initiating any study-related procedures * The participant has received consistent treatment with imiglucerase at a dose ≤ 60 U/kg and ≥ 15 U/kg every other week for a minimum of 30 consecutive months. Participants who are anti-imiglucerase antibody positive will be allowed to enter this study * The participant is at least 2 years of age * Female participants of child-bearing potential agree to use a medically acceptable method of contraception. Male participants must agree to use a medically acceptable method of birth control * Participant must be sufficiently co-operative to participate in the study as judged by the Investigator. Exclusion Criteria: Includes: * The participant has type 2 or 3 Gaucher disease or is suspected of having type 3 Gaucher disease * The participant has received treatment with any investigational drug or device within the 30 days prior to study entry; such use during the study is not permitted * Participant is HIV positive * Participant is hepatitis B/C positive * The participant presents with sustained iron, folic acid and/or vitamin B12 deficiency-related anemia during Screening * The participant, participant's parent(s), or participant's legal guardian(s) is/are unable to understand the nature, scope, and possible consequences of the study * The participant has a significant comorbidity that might affect study data or confound the study results * The participant is unable to comply with the protocol or is otherwise unlikely to complete the study, as determined by the Investigator * The participant has experienced an anaphylactic/anaphylactoid reaction during treatment with imiglucerase * The participant has received miglustat during the 6 months prior to study enrollment * The participant has an active, clinically significant spleen infarction * The participant has active, progressive bone necrosis * The participant is a pregnant and/or lactating female